1. Technical Field
The present invention relates to a liquid discharging apparatus and a discharge state determination method of liquid in a liquid discharging apparatus.
2. Related Art
A liquid discharging apparatus such as an ink jet printer executes a printing process by forming images on a recording medium by discharging a liquid such as an ink, with which a cavity (a pressure chamber) of a discharge section is filled, as a result of displacing a piezoelectric element provided in the discharge section due to driving the piezoelectric element using a driving signal.
In this kind of liquid discharging apparatus, there are cases in which a printing process is performed using a special ink other than normal color ink. For example, JP-A-2014-218670 proposes a technique relating to metallic printing using a metallic ink, which includes a metallic pigment, in order to form an image having a metallic luster.
Given that, in a liquid discharging apparatus, there are cases in which a discharge abnormality, in which it is no longer possible to normally discharge a liquid from a discharge section, occurs as a result of thickening of the liquid inside a cavity, the incorporation of an air bubble in the cavity, or the like. Further, when a discharge abnormality occurs, it is no longer possible to correctly form intended dots, which are formed on a recording medium by a liquid that is discharged from a discharge section, and therefore, the image quality of an image that the liquid discharging apparatus forms on the recording medium, is reduced.
In JP-A-2004-276544, a technique that prevents a reduction in image quality due to a discharge abnormality by detecting residual vibrations that occur in a discharge section after displacing a piezoelectric element through driving thereof using a driving signal, and determining a discharge state of a liquid in the discharge section on the basis of the characteristics of the residual vibrations such as the period length and amplitude of the residual vibrations, is proposed.
Given that, in a case in which a liquid discharging apparatus discharges a plurality of types of ink, and in particular, in a case of discharging a metallic ink and a pigment ink other than a metallic pigment in the manner of metallic printing, the characteristics of the residual vibrations that occur in a discharge section that is capable of discharging the metallic ink differ from the characteristics of the residual vibrations that occur in a discharge section that is capable of discharging the pigment ink. Therefore, in a case in which the type of ink that each discharge section is filled with is not taken into consideration, there is a problem in that the accuracy of determination of the discharge state of liquid in a discharge section, is reduced.